Intro to Animals (Chapter 26.1) and Invertebrate Evolution (Chapter 29)

Intro to Animals (Chapter 26.1) and Invertebrate Evolution (Chapter 29)

Please set up your notebook for Cornell Notes

What is an animal?• Characteristics• Eukaryotic cells have membrane bound organelles• Multicellular• Heterotrophs must eat other organisms for energy• Lack a cell wall• All belong to the domain Eukarya and the kingdom

Animalia

• 2 Main groups• Invertebrates animals without a backbone

• 95% of all animal species• insects, sponges, worms

• Vertebrates Animals with a backbone• Fish, amphibians, reptiles, birds and mammals

Life processes• Feeding and digestion• Herbivores, carnivores, omnivores, scavengers, decomposers• Digestion depends on the complexity of the organisms

• Intracellular digestion food is digested inside the cells of the organism• Sponges

• Extracellular digestion food is digested outside the cells in a digestive cavity, then absorbed into the body cells• Mollusks, arthropods

• Respiration exchanging oxygen and carbon dioxide• Aquatic invertebrates can respire through skin or gills• Terrestrial invertebrates

• Mantle in snails• Book lungs in spiders• Spiracles and tracheal tubes in insects

• Circulation• Small, thin animals just diffuse materials into and out of the body• Complex organisms move blood using a circulatory system and a

heart• Open circulatory system blood is only partially contained in blood vessels;

flows freely over the tissues• Arthropods, some mollusks

• Closed circulatory system blood is fully contained in blood vessels• Annelids, some mollusks

• Excretion• Animals must have a way to get rid of waste products

• Aquatic animals diffuse waste into the water• Terrestrial animals

• Nephridia tubes in annelids and mollusks• Malphigian tubules saclike organs in insects and arachnids

• Response to stimuli• Simple animals like cnidarians have a nerve net

• No central brain• Flatworms and roundworms have a concentration of nerves

in head area called ganglia• More complex animals show cephalization concentration of

nerve cells towards anterior (head) of body

• Movement and support• Hydrostatic skeleton muscles surrounding a fluid filled

body cavity that supports the muscles• Annelids

• Exoskeleton hard outer covering made of chitin• Muscles are attached to the inside of the exoskeleton• Arthropods

• Endoskeleton structural support located inside the body• Calcified plates• Sea stars

• Reproduction• Asexual one parent produces identical clones

• Pros fast• Cons no genetic variation

• Sexual reproduction two parents combine genes to produce variable offspring• Pros genetic variation• Cons slower• Two ways

• External fertilization eggs are fertilized outside of the female’s body• Internal fertilization eggs are fertilized outside of the female’s body

• Cell specialization cells in body have specific tasks• Leads to complexity

• Cells tissues organs organ systems organism

• Development organisms that reproduce sexually begin life as a zygote (fertilized egg)• The zygote divides thru mitosis until it

forms a hollow ball of cells called a blastula

• The wall of the blastula pushes in called gastrulation• Cells differentiate into germ layers

• Ectoderm outermost layer• Mesoderm middle layer• Endoderm innermost layer

• The opening that is created during gastrulation is called a blastopore• The blastopore leads into a tube that

becomes the digestive tract• Protostome mouth is formed from blastopore• Deuterostome anus is formed from

blastopore

• Body symmetry• Radial regular arrangement around a central point

• Sea stars, sea anemones• Bilateral right and left sides are mirror images

• Allows for segmentation• Annelids, mollusks

• Body cavities• Provide a space for internal organs and the development of

specialized regions• Coelom body cavity completely lined with mesoderm

• Coelomate animal with a coelom• Pseudocoelomate animal with a body cavity partly lined with

mesoderm• Acoelomate animal without a coelom